Performance study of LaBr3:Ce detectors coupled to R2083 PM tube for energy and timing characteristics

Journal of Radioanalytical and Nuclear Chemistry - Performance of 1″?×?1″ LaBr3 (5% Ce) scintillator coupled to Hamamatsu R2083 PM Tube has been investigated for the...     

On the derived length of units in group algebra

Let G be a finite group G, K a field of characteristic p ≥ 17 and let U be the group of units in KG. We show that if the derived length of U does not exceed 4, then G must be abelian.     

Waves in shallow water due to arbitrary surface disturbances

Summary The velocity potential and the surface elevation are calculated for the three-dimensional motion of surface waves excited by any local disturbance of the surface of a sea with constant depth. Approximate values of the resulting wave integrals are given for large values of time and distance. The results are illustrated using physically plausible distributions of the initial disturbance. Some features of the waves are discussed.     

Dioxane Dibromide–Mediated Solvent‐Free Synthesis of Vicinal Dibromides

Structurally varied vicinal dibromides have been synthesized in high yield and good purity through highly stereoselective anti‐addition of bromine across the olefinic linkages using dioxane dibromide (DD) under solvent‐free conditions.     

Study of the Release Mechanism of Terminalia chebula Extract from Nanoporous Silica Gel

Sol/gel-derived silica gel was prepared at room temperature from tetraethyl orthosilicate precursor. The extracts of Terminalia chebula (Haritoki) were entrapped into the porous silica gel. Fourier transform infrared analysis revealed the proper adsorption of herbal values in the nanopores of the silica gel. Porosity was estimated by transmission electron microscope studies. The release kinetics of the extract in both 0.1 N HCl, pH 1.2, and Phosphate-buffer saline (PBS), pH 7.2, were determined using UV–Vis spectroscopy. Different dissolution models were applied to release data in order to evaluate the release mechanisms and kinetics. Biphasic release patterns were found in every formulation for both the buffer systems. The kinetics followed a zero-order equation for first 4 h and a Higuchi expression in a subsequent timeline in the case of 0.1 N HCl. In the case of PBS, the formulations showed best linearity with a first-order equation followed by Higuchi’s model. The sustained release of the extract predominantly followed diffusion and super case II transport mechanism. The release value was always above the minimum inhibitory concentration.     

Evidence of formation of tetravacancies in uniformly oxygen irradiated n-type silicon

High purity n-type silicon single crystal with resistivity in the order of 4000 Ω cm has been irradiated with high-energy oxygen ions at room temperature up to a fluence of 5E15 ions/cm². The energy of the beam was varied from 3 to 140 MeV using a rotating degrader to achieve a depthwise near-uniform implantation profile. Radiation induced defects and their dynamics have been studied using positron annihilation spectroscopy along with isochronal annealing up to 700 °C in steps of 50 °C for 30 min. After annealing the sample at 200 °C for 30 min, formation of silicon tetravacancies has been noticed. The formation of the tetravacancies was found to be due to agglomeration of divacancies present in the irradiated sample. An experimentally obtained positron lifetime value of 338±10 ps has been reported for silicon tetravacancies, which has a very close agreement with the value obtained from recent theoretical calculations. The tetravacancies were found to dissociate into trivacancy clusters upon further annealing. The trivacancies thus obtained were observed to agglomerate beyond 400 °C to form larger defect clusters. Finally, all the defects were found to anneal out after annealing the sample at 650 °C.